A collaboration of two labs at the Morehouse School of Medicine (Drs. Bond and Powell) have been[unreadable] investigating the possibility that soluble Nef, secreted from HIV infected cells, is responsible for a significant[unreadable] portion of the T-cell depletion that is a hallmark of HIV pathogenesis. Our research group has developed a[unreadable] body of results that support a key role for Nef in T-cell depletion. We have been funded to do a pilot study to[unreadable] begin to examine this overall theory in Rhesus macaques. However, there remain a number of key issues[unreadable] revolving around the mechanics of how secreted Nef induces the apoptosis of T-cells leading to[unreadable] pathogenesis. The focus of this proposal is on two key aspects of Nef-induced T-cell depletion and is[unreadable] addressed in this proposal through the hypothesis that Nef protein is secreted from HIV infected cells in[unreadable] vesicular form and induces an apoptotic signal in non-infected T-cells through key interactions between the[unreadable] Nef apoptotic motif (M1) and the amino terminal domain of CXCR4. Questions regarding the secretion of[unreadable] Nef from HIV-1 infected cells (Dr. Powell's lab will be lead group), will be addressed in the following AIMS:[unreadable] AIM 1: Demonstrate that Nef is secreted from transfected and infected T-cells and characterize the secreted[unreadable] vesicular bodies; AIM 2: Determine if mutations outside of the Nef apoptotic region influence induction of[unreadable] apoptosis or incorporation of Nef into vesicles. Questions regarding the detailed interactions between Nef[unreadable] and the CXCR4 receptor (Dr. Bond's lab will be lead group) will be addressed in the following AIMS: AIM 3:[unreadable] Determine those amino acids on the Nef apoptotic motif 1 and on CXCR4 critical to Nef-binding and[unreadable] apoptosis; AIM 4: Determine whether other nonstandard CXCR4 ligands follow the same rules of interaction.[unreadable] Together these results should provide a more complete picture of the mechanics of secreted Nef induction of[unreadable] apoptosis in T-cells leading to the progression toward AIDS.